Chronic obstructive pulmonary disease (COPD) is a chronic, slowly progressive disorder characterized by airflow obstruction (associated with aberrant airway inflammation) and airway remodeling. COPD symptoms can present with airway tissue damage. Airflow limitation is slowly progressive, leading to dyspnoea and limitations of physical exercise capacities. However, impairment is not restricted to the lungs, as COPD patients are also at higher risk for systemic failures including cardiovascular diseases.
The clinical presentation of COPD can vary in severity from simple chronic bronchitis without disability to a severely disabled state with chronic respiratory failure. The diagnosis of COPD is usually suggested by symptoms, but is typically only established by quantitative measurements, preferably using spirometry.
COPD is the fourth leading causes of death worldwide and the only major disease with an increasing death rate. By 2020, it is estimated that only ischemic heart disease and cerebrovascular disease will account for a higher mortality among the world's population. Prevalence and hospitalization rates have increased dramatically over the past years. According to statistics from the National Institute of Health (NIH), 12 million adults in the U.S. are diagnosed with COPD, and 120,000 die from it each year. An additional 12 million adults in the U.S. are thought to have undiagnosed COPD. COPD accounts for 1.5 million emergency room visits and over 700,000 hospitalizations annually, with an estimated cost to the US healthcare system of over $32.1 billion in 2001. COPD death rates for women have risen steadily. Today, more women than men die from COPD each year.
There is a scarcity of available information and extremely low public awareness about COPD. There are few efficacious alternative treatments available. Lack of awareness and the insidious nature of the disease have been major contributing factors to the low diagnostic rates seen in COPD. As the symptoms of the disease occur with the onset of middle age, many patients dismiss symptoms such as breathlessness upon exertion as old age. Smokers, who constitute the majority of COPD sufferers, also commonly dismiss symptoms, such as chronic cough, as something to be expected because of smoking, rather than an indication of a serious underlying problem.
The Nocturnal Oxygen Therapy Trial supported by the NIH showed that patients with advanced COPD live longer with long-term oxygen therapy. Clinical trials sponsored by the National Heart, Lung, and Blood Institute and the Centers for Medicare and Medicaid Services are investigating the effectiveness of oxygen treatment for increasing life expectancy in patients with moderate COPD.
Heliox is a breathing gas composed of a mixture of Helium (He) and Oxygen (O2). Heliox generates less airway resistance than air and requires less mechanical energy to ventilate the lungs, reducing the Work of Breathing (WOB). While oxygen alone may reduce breathlessness, heliox reduces resistance in the lungs during exhalation, which allows COPD patients to exhale more air. This means the lungs can better eliminate carbon dioxide from the body. According to results of a randomized, crossover trial, a combination of helium and oxygen improves walking distance in patients with COPD. Wedzicha, American Journal of Respiratory and Critical Care Medicine, 173(8):825-826 (2006). In another, smaller study, giving heliox during exercise allowed a greater amount of air to be inhaled by the lungs and reduced shortness of breath scores compared to those who were on room air. Heliox induced a state of hyperventilation, which reduced carbon dioxide levels in the blood of patients studied, increasing exercise capacity. See Palange et al., J Appl Physiol, 97:1637-1642 (2003).
Although medical uses of heliox have been known since the 1930s, it is typically only administered in settings such as a hospital or modern specialist respiratory centers. Systems used in these settings rely on an invasive ventilator system or non-invasive open-circuit breathing systems to deliver heliox treatment. Open-circuit breathing systems are inefficient for delivery of heliox because a portion of the gas escapes into the atmosphere prior to reaching a patient's lungs and helium is lost to the atmosphere upon exhalation. This results in as many as four to six full-sized tanks of heliox being required for 24 hours of treatment. Helium is over 13 times as expensive as oxygen. Therefore, current heliox treatments are inconvenient and cost-prohibitive for many patients.
Closed-circuit breathing apparatuses have been developed for applications requiring complete respiratory protection in potentially hazardous conditions, such as decontamination, urban search and rescue, or biohazard situations. Exhaled carbon dioxide is typically removed by an in-line carbon dioxide scrubbing device. These systems typically deliver only pure oxygen or standard or enhanced breathing air mixture, similar to that used during scuba diving. Currently available closed-circuit breathing apparatuses are not configured to regulate a mixture of heliox. Further, current closed-circuit breathing apparatuses can only function for limited durations (e.g. 4 hours or less). Thus, current closed-circuit breathing apparatuses are not suitable for long term (i.e. overnight) use.
The amount of oxygen within the closed-circuit is regulated by standard in-line and/or tank regulator that is manually adjusted prior to or during use. Therefore, a user must be conscious in order to operate the breathing apparatus. As such, current closed-circuit breathing apparatus are unsuitable for use in sleeping or otherwise unconscious individuals.
There exists a need for improved heliox treatments.
It is therefore an object of the invention to provide improved systems and methods for heliox delivery to an individual suffering from COPD or symptoms thereof or related diseases or disorders.
It is a further object of the invention to provide more cost effective systems and methods for heliox delivery.
It is an additional object of the invention to provide systems and methods for heliox delivery that can be routinely employed outside the hospital setting, such as in a patient's home.